The mobile communication field is one of the industries with the fiercest competition. Telecommunication operators are increasingly requiring differentiated services to enhance their competitiveness, and NGN technologies with soft switch and packet switch technologies as a core have become a focus in the industry. Stream media is a form of network multimedia emerging in recent years, and with the support of stream media, transport of multimedia information such as video, audio over a network has evolved from previous download manner to a stream transport manner.
FIG. 1 is a schematic diagram of a typical networking mode for a PROXY in the NGN network. As illustrated in FIG. 1, the PROXY is one of important devices in the NGN. For an end user in the NGN, the PROXY is equivalent to a server; and for a core server in the NGN, the PROXY is equivalent to a terminal. A PROXY is required to support one or more proxy functions in the protocols of Session Initiation Protocol (SIP), H.323, Media Gateway Control Protocol (MGCP), and H.248. Because the PROXY participates in the entire signaling processing flow, the PROXY may obtain detailed information in signaling on user registration, call, etc. The PROXY generally includes tow parts, i.e. a Signaling Proxy and a Media Proxy.
The Signaling Proxy (SP) is adapted to process messages of registration, call, etc., of an end user. The messages of registration, call, etc., of the end users are firstly sent to the PROXY. The PROXY forwards the messages to a core soft switch system after signaling processing. The core soft switch system returns the received messages of registration, call, etc., to the PROXY after signaling processing, and the PROXY forwards the messages to a user terminal after signaling processing.
The Media Proxy (MP) is adapted to act as a proxy for a media stream of video, audio, etc., of an end user. All media streams intercommunicated between the end user on behalf of whom the PROXY acts and the external are processed and forwarded by the PROXY. When the end user attached to the PROXY acts as a caller, a called as seen by caller is the PROXY, and the address of the called as seen by the caller is the address of the PROXY.
Both the SP and the MP are logical concepts. An SP can communicate with one or more MPs and may be integrated with an MP in one device. An SP and an MP may also be implemented respectively with separate devices or be implemented by being integrated in other devices such as an edge session controller and a firewall.
In order to overcome the scarcity of IPv4 addresses, most corporations dispose a Network Address Translation (NAT) device at a network egress, which translates an internal private network address into an address for accessing a public network. In order to improve network security, most corporations dispose a Fire Wall (FW) at the network egress. In a practical application, the firewall and the NAT device are typically implemented by being integrated in one entity which functions to both translate an internal address and improve network security.
FIG. 2 is a schematic diagram of a typical networking mode for the PROXY in the NGN network with the NAT/FW. As illustrated in FIG. 2, some terminals such as a terminal 1 and a terminal 2 have an access to the PROXY through the NAT/FW, and some terminals such as a terminal 3 and a terminal 4 are connected to the PROXY.
A terminal may fail during practical operations, for example, the terminal is not able to be put through. At this time, network maintenance personal wish to find the exact reason why a service cannot be carried out for the terminal as soon as possible, for example, a fault of the terminal, a fault occurring in the NAT/FW device or a fault of the network.
A fault detection method in the related art detects and locates a fault by sending a probing (PING) command and a route probing (TRACEROUTE) command of the network layer to an IP address of a user terminal.
The function of the PING command is to detect whether the user terminal is accessible from the network layer by PINGing the IP address of the user terminal. In other words, whether the user is accessible from the network layer.
The function of the TRACEROUTE command is to detect a route forwarding path to the user terminal and to locate a route fault point by TRACEROUTEing the user terminal.
The existing fault detection method has the following characteristics.
1. The use of the PING and TRACEROUTE commands is forbidden on the firewall, at least a host outside the network is forbidden to PING or TRACEROUTE a host inside the network, and therefore a connection condition of the network provided with the firewall may not be detected effectively through the PING and TRACEROUTE commands.
2. In a practical application, a NAT device is commonly disposed over the network, a request to a user terminal may reach the soft switch system only if the user terminal passes through one or more NAT devices, and an IP address allocated to the user terminal is typically a private network address. Consequently, the PING or TRACEROUTE command sent from the PROXY to the user terminal may not traverse the NAT device(s), i.e. a condition of the network connection from the NAT device(s) to the user terminal may not be detected.
3. In a practical application, an IP address of a user terminal is generally allocated dynamically. For example, the IP address is obtained through the Dynamic Host Configuration Protocol (DHCP) or other dynamic manners. Consequently, no PING or TRACEROUTE operation can be performed unless the IP address of the user terminal is determined regardless of whether the NAT/FW device is present in the network.